Cutinase Promotes Dry Esterification of Cotton Cellulose Zhao Xiaoman Key Laboratory of Eco-Textiles Ministry of Education, Jiangnan University, Wuxi 214122, P.R.China Matama Teresa, Ribeiro Artur, and Silva Carla Centre of Biological Engineering (CEB), University of Minho, Braga, Portugal Wu Jing State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, P.R.China Fu Jiajia Key Laboratory of Eco-Textiles Ministry of Education, Jiangnan University, Wuxi 214122, P.R.China National Engineering Laboratory for Modern Silk, Soochow University, P.R.China Cavaco-Paulo Artur Centre of Biological Engineering (CEB), University of Minho, Braga, Portugal International Joint Research Laboratory for Textile and Fiber Bioprocesses, Jiangnan University, Wuxi 214122, P.R.China DOI 10.1002/btpr.2194 Published online November 28, 2015 in Wiley Online Library (wileyonlinelibrary.com) Cutinase from Thermobifida fusca was used to esterify the hydroxyl groups of cellulose with the fatty acids from triolein. Cutinase and triolein were pre-adsorbed on cotton and the reaction proceeded in a dry state during 48 h at 358C. The cutinase-catalyzed esterification of the surface of cotton fabric resulted in the linkage of the oleate groups to the glycoside units of cotton cellulose. The superficial modification was confirmed by performing ATR- FTIR on treated cotton samples and by MALDI-TOF analysis of the liquors from the treat- ment of the esterified cotton with a crude cellulase mixture. Modified cotton fabric also showed a significant increase of hydrophobicity. This work proposes a novel bio-based approach to obtain hydrophobic cotton. V C 2015 American Institute of Chemical Engineers Biotechnol. Prog., 32:60–65, 2016 Keywords: biocatalysis, cellulose, cutinase, dry esterification Introduction Cutinase (E.C. 3.1.1.74) is a serine esterase whose natural substrate is cutin. Cutin, the structural component of the outer envelope (the cuticle) of higher plants, is a polyester. Cutinase is produced mainly by plant pathogens and it hydrolyzes the ester bonds of cutin thereby releasing fatty acids. Besides its natural substrate, cutinases are described to catalyze the hydrolysis of a variety of polymers, insoluble triacylglycerols, and low-molecular-weight soluble esters. 1 In low water conditions, cutinases are also described as able to catalyze esterification and trans-esterification reactions. 1 This versatile catalytic ability of cutinase is also described in a wide range of fiber modifications like wool anti-felting, 2,3 cotton bio-scouring, 4,5 and even synthetic fibers modifica- tion. 6–8 The enzymatic esterification of Avicel and cotton cellulose was reported 9 using wild-type cutinase from Fusar- ium solani and an engineered cutinase, fused with the carbohydrate-binding module N1 from Cellolomonas fimi. The surface esterification of hemicellulose films catalyzed by lipases from Mucor javanicus, Rhizopus oryzae, Candida rugosa and by a cutinase from F. solani pisi is reported by others. 10 The specificities of cutinase and lipases were com- pared. Lipase presented higher activity toward long alkyl chain substrates while cutinase presented higher activity toward shorter alkyl chain substrates. The interest in cellulose esters is evident from the diversity in type and applications of functionalized cellulose. 11 Most developed processes involve homogeneous reactions where cellulose solubilization is a prerequisite. 12 However, many industries, such as the paper and textile industries, have a par- ticular interest in the hydrophobization of the cellulose surface rather than the extensive cellulose modification. Hydrophobic surfaces are important because of the particu- lar properties that they confer to a material such as water repellency, self-cleaning, friction reduction, and antifouling. 13 From the textile industry perspective, surface modifications of cotton with long hydrophobic molecules would also improve the perception of softness, which can be considered to be an added-value. Traditional softeners are cation-active, anionic, nonionic surfactants that include waxes, paraffin, microemul- sions, and other polymers. In the case of cotton, the cationic softeners ideally establish electrostatic bonds with cellulose fibers, so that the hydrophobic ends (which give soft handle) are directed outwards. 14 Despite its hydrophilicity, cellulose has unmatched advantages as a substrate for the production of Correspondence concerning this article should be addressed to C.-P. Artur at artur@deb.uminho.pt. 60 V C 2015 American Institute of Chemical Engineers